Parameterization and optimization strategies for the automated design of uPVC profile extrusion dies

Optimization strategies for use within an automated optimization framework for PVC profile extrusion dies are presented. The methods are designed to work in an industrial environment and must therefore account for the specific design and manufacturing techniques for these profile dies. The complex three-dimensional die geometry will be represented through a series of two-dimensional so-called 'die-slices'. The purpose of the presented optimization cycle is to find the optimal shape of the die cross-section of the die-slices. Each die-slice geometry is optimized by a computerized optimization loop using a finite element (FE) analysis of the polymer flow through the die. Simple data representation of the complex die geometry allows an efficient parameterization. Several optimization strategies are compared regarding the achieved quality of the optimization, the computational costs, the required user interaction and the robustness in industrial applications. The strategies are (i) a global scheme in which all design variables (DVs) are dealt with simultaneously, (ii) a sequential optimization in which DVs are addressed one after each other, (iii) employing a height approximation type method in which the new values for the DVs are found using assumptions of the flow between two parallel plates, and (iv) a global scheme in which the DVs are decoupled taking advantage of the particular FE analysis applied.